Within the field of indoor horticulture, it is commonly known that adjustable light fixtures offer many advantages, such as allowing horticulturists to customize the intensity and geometry of light radiation emitted from a light fixture to meet the needs of plants at different stages of growth, without adjusting the height at which the light fixture is installed, replacing the fixture, changing the lamp used or making other such changes.
Typically, a light fixture is installed above a planting tray of standard dimensions: 4 ft×4 ft, 4 ft×6 ft or 4 ft×8 ft. It is commonly known that plants require different intensities of light for optimal results at different phases of growth, creating the need for a light fixture capable of emitting a light beam of uniform intensity which can be easily adjusted to a plurality of selected geometries, which correspond to both the standard dimensions of commonly used planting trays and selected degrees of intensities commonly required for optimal results at different stages of plant growth.
In the prior art, adjustable light fixtures which comprise at least one arched, concave reflective surface have no end plates along the curved edges of the reflective sheet, thereby failing to reflect light emitted from the central light source toward the sides of the fixture not bounded by the arched sections of the reflective surface. Such arrangements fail to reflect substantial amounts of light radiation into the target area, resulting in a waste of electricity.
Another shortcoming not addressed in the prior art is the inability to adjust the geometry of the light beam emitted by a light fixture in a single step and without the use of additional tools. Previous art requires multiple steps or the use of tools to adjust the geometry of the emitted light beam. Due to the complexity of the adjustments, horticulturists must spend substantial time and exert substantial effort to carry out the adjustments, which in most practical growing situations must be carried out for a large quantity of light fixtures. In addition, the need for the precise use of hand tools requires a sufficiently high level of visibility in the field. This necessitates the installation and operation of auxiliary lighting sources in the work space, which necessarily incurs additional costs.
In the prior art, light fixtures with concave reflective surfaces substantially surrounding the light source on five sides are built with substantially heavy frames or housings to support the light source and the reflective surfaces. The weight of the fixtures increases the difficulty of installation and necessitates that the structure or architecture supporting the fixture is able to support a heavy object. A rigid housing comprising a latitudinal surface above the light source and rigid, longitudinal sides surrounding the light source limits the degree to which reflective surfaces installed within the concave structure can be easily adjusted, and the necessary complexity and heaviness of the fixtures increase manufacturing and shipping costs.
In the prior art, adjusting the concavity of fixtures with arched reflective surfaces requires changing the degree of curvature of the arched surfaces, which may result in sub-optimal geometries of the reflected light beam or sub-optimal uniformity of the radiation intensity of the light beam.